During the dog days of summer in Livingston, Montana, at the Murray Bar in the evening, there is a faint air of shared chagrin. As one of the fishing guides, you're easily identified, a sunglass tan line, shaggy hair protruding from a baseball cap. The clients – "sports," as we call them – stand out as well: overweight, sunburned, new Columbia fishing shirts and Sperry Top-Siders, southern accents. They buy the drinks; you slump on the bar and summon up whatever bits of good humor you still have left, waiting for the sports to leave for their dinner reservations. When they go, there is a collective exhalation, an almost palpable sense of relief. New drinks are ordered. Then the ritual: You dig in your pocket and count the sweaty roll of bills that was pressed into your hand at the boat ramp at the end of the day. The sacred tip. The hundreds go into the safe box at home; the small bills go toward your bar tab. At that point you either grumble about what a cheap bastard you had or you celebrate your good fortune by buying a round. Then the fishing talk commences. What stretch did you float? How horribly inept were your people? Did you get hit with that damn east wind? The general consensus is that it is pretty brutal.

"Fuck," someone inevitably says. "Getting a real job is starting to look good. I don't know how much longer I can do this." We all nod and agree. As if we are all desirable employees, like all we'd have to do is tune up our résumés and the "real" jobs would be ours for the taking. What we are, however, are college dropouts, liberal-arts-degree-wielding suckers, pothead ski bums, trust-funders in need of tax write-offs, PTSD-suffering veterans, high-functioning alcoholics, corporate refugees – all of us people who have, for one reason or another, found solace in a life spent on the river, or at least at some point were attracted to the idea of it. The truth is, most of us aren't suited to much else. We live where other people take their vacations; we say that to each other like a mantra. Sometimes in February, when the money has run out, we say, "You can't eat the scenery." That might be a mantra, too, but it's the bitter kind.

Despite the recent recession, the fly-fishing business remains fairly steady – these days there are more guides working the river than ever. Guides in Montana are required to display their guide license number on a red tag on their boat. The old-timers, fewer each year, have numbers in the low hundreds. This year some amped-up college freshman at Montana State will get his license, and it will approach the 20,000s. This increase in numbers breeds competition, and it doesn't help that guides as a whole are prone to a level of confidence that often crosses the line to arrogance. I call it the God complex. Every day you're the master of your little domain, the acknowledged expert. Your sports, usually highly successful people, bow to your judgment. If you're not careful, this can lead to an inflation of ego – a situation in which bragging at the end of the day about the number of fish your clients caught is just the beginning of a more dangerous downward slide toward the insufferable.

In this town, everyone takes wealthy fishermen down the Yellowstone River, or serves them drinks, or makes them their dinner, or fixes their car, or helps them build their 8,000-square-foot log totem to ego in Paradise Valley. If you could somehow track all the little trickles of income moving downstream to those who depend on it for a living, I think the picture would look a lot like the river itself, tributaries branching and splitting. The river is the artery that supplies the lifeblood to all the veins and capillaries keeping the extremities moving.

This is my 10th year guiding. When I was 19, I built a wooden drift boat in my parents' garage and headed, as they say in Michigan, "out west." If I've learned anything in that time, it's that over the course of a day on the river, something good will happen if you keep your head in the game. If you keep your sports casting, no matter how bad they are, the river will reward you. Something will happen. It always does. Even at the end of the summer, when the fishing is slow due to the heat and the clients seem especially difficult, if you just wake up every morning and get the coffee going, take a shower to shake off the hangover, and put the Bob Marley on in the truck on the way to the river, eventually you will have the day. The best day. Every season has its worst day, and every season has its best day. This year my best day had little to do with the fishing itself. What made it epic was the company.

It's 8 a.m. and the authors Jim Harrison and Peter Matthiessen are standing on the sidewalk in front of my rig. At 75 and 86, respectively, they have more than 60 published books and several major literary awards between them. Harrison's novella 'Legends of the Fall' remains, despite its brief 80 pages, a monumental story in every sense of the word. Matthiessen's book 'The Snow Leopard' is a treatise on spirituality cloaked in a damn good Himalayan adventure story. At this point, both of these men seem to me a rare, possibly vanishing breed of writer – there is an easy authenticity regarding the natural world to be found in both of their styles, one that can stem only from lives lived out of doors. Friends since meeting at Stony Brook University in the mid-1960s during Harrison's brief teaching tenure there, the men have fished together in Montana for decades. Today, I'm filling in for their regular guide, who is busy butchering a pig. Harrison and Matthiessen both walk with canes. I hope neither of them decides to cash in his chips while I'm rowing them down the river.

As I'm getting the boat ready to launch, Harrison recounts an incident from a few years ago. He'd been at this same spot and seen a girl swimming in the river. She'd gotten out and wriggled back into her shorts. "She was wearing white panties," he says, his voice sounding like a drift boat being dragged over a mid-river gravel bar. "She was all wet, and she knew I was looking at her, and she took her time. She must have known I was an American Poet. I could have used a bib."

Peter is shaking his head and smiling.

I help them into the boat and stow their canes. It is clear and warm. We float east of Livingston, where the land starts to flatten out. There are large ranches here, few houses, great swaths of dead brown grass. Train tracks run parallel to the river, and sometimes a whistle shatters the stillness. Peter is as soft-spoken as Harrison is ribald and loud. Both of the men handle the fly rods well. They talk about fishing trips past, and it is clear that they like each other a great deal.

We catch a few trout and lose a few more. At one point, Peter, trying to avoid an errant cast from Jim, gets his line tangled. As I'm fixing it, Jim says, "Peter, stop being so goddamn high-maintenance; you're going to have to leave the tip if you keep this up."

A while later, a large brown trout moves for Harrison's fly, and he isn't paying attention and does nothing to set the hook. "Oh, damn," he says, fumbling for his American Spirit cigarettes. "That's how it always goes. I was watching the U.S. Open last night. I was thinking about Serena's big ass right there. I fucked that up." This gets a laugh from Peter, and I relax.

I've seen it over and over, the way fly-fishing brings everyone down to the same basic level. In the boat, these two aging but still brilliant literary minds rag on each other about missed fish and bad casts, talk about women, and bitch about being broke, just like my friends and I do.

Harrison asks me if I'm married. I'm not, but I tell him about my most recent girlfriend, a wildly beautiful musician and rock climber who had, just a few days ago, out of the blue, loaded up her van and left to go play her ukulele and work on a marijuana farm in Northern California. It's kind of ridiculous, I realize, but she really was fantastic, and it stings. In Montana, we say, "You don't get a girlfriend; you just get your turn."

Harrison laughs when I tell him this. "Most fishing guides I know are alcoholics and behind in their child support payments," he says, "so I guess you're doing okay."

If I could picture a more perfect Montana, it would be exactly the same as it is now, just with the occasional busload of females from Austin, Texas. Summers are one thing: Tourists abound, strange, interesting women blowing through from parts unknown. Winter, though, the same faces, the girls who already know you for what you are – another commitment-phobic fishing guide with a Peter Pan syndrome. I tell myself that with her gone, I'll get more writing done, I'll be able to focus. In truth I'll probably just be out running around, chasing girls, writing even less. I look at Matthiessen – who won the National Book Award for the third time at age 81 – and consider the possibility that there might come a time in every writer's life where the worldly concerns fall away and the work becomes the realest part of his existence. Probably this is wishful thinking. Either way, I can't decide if this is something to dread or look forward to.

In all fairness, I guess the women here have a saying, too: "The odds may be good, but the goods are odd."

I pull the boat into the shade for lunch. Harrison, renowned gourmand that he is, has learned over the years never to put the serious matter of his midday repast in the hands of his dirtbag fishing guide. I dig in the cooler. There is a large, oregano-scented hard salami sent from Jim's friend chef Mario Batali in New York. A huge block of Manchego cheese, a loaf of crusty bread, a jar of pickled hot peppers. I cut the salami and cheese and rip hunks of bread, and we pass the cutting board around.

For the first time, I bring up writing. I ask them what they're working on. As it turns out, both of them have just completed new novels. I ask them if they write every day, and both say yes, for the most part. Their work ethic shames me. I haven't written anything in months, since before the guide season started. Being around these two makes me wonder if there will ever come a day when I can call myself a writer and actually believe it.

I have a million questions I'd like to ask, not the least of which is if they would ever blurb my book if or when it ever comes out. But I'm also acutely aware of my role here. I'm their 29-year-old fishing guide. They have hired me to perform a service. When I guide investment bankers, I don't pester them for stock tips. When I guide chefs, I don't ask them about recipes. People come fishing to get away from their work, and it's important, as a guide, for me to keep that in mind.

Sometimes the clients will talk among themselves – especially on corporate trips – exclusively about the office, and it's your job to get them out of that mind-set. They are standing in a drift boat in the middle of the Yellowstone River under the shadow of the Absaroka Mountains with trout rising all around them, and they will talk over your head about the price of sweet crude and flow rates and what the market did that morning. I put up with this for only so long. If it gets unbearable, I will get their attention gently. "Hey, guys," I will say, interrupting their jargon. "Maybe we put the cell phones away for a bit?" Or, always a favorite, "How about we talk about pussy for a while?" At the end of the day, these men thank you for this.

So, with this in mind, I don't press Peter for details about his time in France after WWII when he founded 'The Paris Review' as a front while working for the CIA, or Harrison about his drug-addled days tarpon fishing in Key West in the sixties with Tom McGuane and Richard Brautigan. Instead I point to the sky. "Check out the pelicans," I say.

A group of the birds are flying in tight formation over the river. They pass between us and the sun, and we can feel the shadows of their wings cross our face.

"Spectacular," Peter says. And then we resume fishing.

Over the course of the afternoon, the men start talking about writing without my prompting. Harrison says that he is getting too old to write novels, that maybe the one he's just completed will be his last. Matthiessen snorts at this. "Hell,'' he says. "I don't want to hear that out of you. Look at me; I'm like Father Time."

We float in silence for a while, and then Harrison says, "I've been thinking – I'd like my gravestone to say, 'He got his work done.' " There is a very clear sense that this might be one of the last days, if not the last, these two spend on the water together, and I suppose a river is as good a setting as any to ponder mortality.

In the late afternoon, we drink our beer beside the river. It has been under ice all day and is teeth-achingly cold and good. They thank me for the trip, and we load up in the truck. Harrison immediately fills the cab with cigarette smoke. We talk about dogs all the way back to town.

That evening I write "he got his work done" on a sticky note and put it up above my neglected writing desk. This appeals immensely to my Midwestern sensibilities, my ingrained Lutheran work ethic and guilt complex. It's an epitaph to aspire to. But for now, it will have to wait. I have to guide again tomorrow and most of the days after that until mid-October. Tonight, still, I have to clean out my boat, deodorize the interior of my truck, arrange for lunches, and confirm meeting times.

I stop at the Murray Bar for a quick one. Everyone is there. I'm feeling a rare tinge of the magnanimous, and I buy a round. The nights are starting to get cooler. In a few days you will be able to see your breath in the morning. There has been a shift; the end is in sight and spirits are high. I stay later than I had planned, talking about fishing. Then the band starts and the girls show up and we are dancing. Eventually a few sports straggle back in after their dinners. They sit off to the side and watch us, the locals – the fishing guides and the waitresses, the construction workers and the massage therapists – swinging around the sweaty, packed dance floor. We are off duty now, and they know it; they keep their distance. These men are CEOs of large companies, lawyers, judges, doctors, bankers. Everyone is a local somewhere, I suppose, but in moments like these, you can see it in their eyes, a wistfulness, feel them wondering what it would be like to be a local here. They are thinking, "If I had done things a little differently, what would my life look like?"

Later, half-drunk and dead tired, falling into bed, I check my phone, hoping, I won't lie, for a message from my errant woman. Instead, there is a voice mail from Harrison.

Yeah, this is Jim Harrison. I just woke up from my nap. I'm going to be writing for a few days, but I'd like to fish again next Sunday. You're probably at the bar. Be careful with those girls you hang out with; they can do evil to your art. Okay, bye-bye.